Lighting device.



G. A. MAGBETH.

LIGHTING DEVICE.

APPLICATION FILED JAN. 15, 1910.

979,181, Patented Dec. 20, 1910.

2 SHEETS-SHEET 1 E INVENTOR G. A. MAOBETH. LIGHTING DEVICE. APPLICATIONFILED JAN.15, 1910.

2 SHEETS-SHEET 2.

WITNEWJA/ nevsn'ron Patented Dec. '20, 1910.

NltTltlD @TATEh PATENT @FFTQE GEORGE A. T'IIACBE'IH, OF PITTSBUrtG,PENNSYLVANIA.

LIGHTING DEVICE.

To all whom it may concern:

Be it known that I, Gnoncn A. lwlaonn'rir, a citizen of the UnitedStates, residing at Pittsburg, in the county of jilleg eny and State ofPennsylvania, have invented certain new and useful Improvements inLighting Devices, of which the following is a specification.

The invention relates to lamps and particularly to the lenses employedtherein. It has for its primary objects; the provision of a lens of theechelon type wherein the ridges are so formed as to secure a broaderband of light; the provision of a lens of the echelon type wherein theridges are divided transversely so as to secure a plurality of fields orhands of concentrated light; and the provision of a lens having thislatter characteristic and in which the rays through the side portions ofthe lens are bent inwardly thereby reducing the field of illuminationand increasing the intensity of such field. These and such other objectsas may hereinafter appear I attain by means of a device shown inpreferred form in the accompanying drawings, wherein *igure 1 is a frontelevation of a lamp provided with my improved lens,

Figure 2 is a section on the line IIII of Figure 1,

Figure 3 is a side elevation partially broken away 011 the line IIIIIIof Figure l, and

Figure 4 is a section through the lens on the line IVTV of Figure 2.

On reference to the drawings it will be seen that the lens employed is,in general, of the echelon type, and is shown applied to a switch lamp Aof ordinary construction provided with illuminating means B and areflector C, which may be of any desired type. In the echelon lensesheretofore employed the retracting ridges were continuous across thelens and were formed on the same radius of curvature as the lens, thevisual efiect of which is a thin vertical strip of light. One of thechief objects of my invention is to broaden this strip or band of light,thereby increasing the lighting power and utility of the lamp. Iaccomplish this by providing sets or series of refracting portions orridges 1 and 2, and 8, at and 5, each of which is formed on a radiussmaller than that of the lens in general, and constitutes in efiect alens in itself. This construction shortens the focus and therebybroadens Specification of Letters :Patent.

Application filed January 15, 1910.

Patented Dec. 20, 1910.

Serial No. 538,326.

the band of light, the increased illumination secured therefrom beingparticularly useful in switch lighting in heavy weather, and in lightsfor vessels. Another result obtained by thus dividing the refractingridges into sets of lenses is the formation of a plurality of fields orbands of concentrated light 6, 7 and S, as indicated diagrammatically inFigure 2. This arrangement has been found to give a better illuminationin front as well as at an angle and gives the lamp a distinctiveappearance. The construction is also desirable in that the outermostrays of light (Figure are bent inwardly, thus giving a more restrictedfield of illumination for each portion, but providing a more intensefield more nearly in front of each portion and at a point where it is ofgreatest advantage. It is of course immaterial insofar as the broadinvention is concerned whether or not the particular configuration ofthe ridges be as illustrated, or whether the ridges be placed upon theouter face of the lens, or glass.

Having thus described my invention and illustrated its use, what I claimas new and desire to secure by Letters Patent is the following l. Acurved lens provided with a plurality of horizontal ridges having suchridges divided vertically into sets, the sections of each set of theridges being convex horizontally.

2. An echelon lens having a plurality of substantially horizontalparallel ridges, each separated into sections thickest at the cen tersof the sections and tapering inwardly to the ends, correspondingsections of different ridges being in substantially vertical alinement.

3. A lens having on its face a plurality of vertical rows of convexrefracting ridges, the refracting ridges in adjacent vertical rows beingend to end and in substantially horizontal alinementr 4. A lens havingon its face a plurality of horizontal rows of elongated convexrefracting portions arranged in series one above the other, each rowcomprising a plurality of portions placed end to end and the corresponding portions in the various rows being in vertical alinement.

5. In combination in a lamp having a source of illumination, aparti-cylindrical lens having a substantially plane rear face and afront face having a central refracting portion, and side retractingmeans each comprising a series of horizontal ridges in substantiallyvertical alinement and having the thickest portions at the center anddecreasing in thickness from the center to the ends. A

6. In combination in alamp having a source of illumination, aparticylindrical lens having a central portion and retracting means ateach side thereof, each of such retracting means comprising a series ofhori zontal ridges in substantially vertical aline ment and having thethickest portions at the center and decreasing in thickness from thecenter to the ends.

In testimony whereof I have hereunto signed my name in the presence ofthe tWo subscribed Witnesses.

GEO. A. MACBETH.

Witnesses g HARVEY L. LECI-INER, DOERIKG BELLINGER.

